This invention relates to a method for preparing cooked or pre-cooked bacon, and more particularly to a method for preparing cooked or pre-cooked bacon in a continuous manufacturing process without a traditional curing and smokehouse process.
Traditional curing is accomplished by injecting salt, either alone on in combination with sodium or potassium nitrite, to the green (uncured and unsmoked) pork belly and allowing it to disperse throughout the meat and allowing the meat to mature in the presence of the curing ingredients. The curing ingredients are commonly incorporated into a brine solution (hereinafter referred to as the "pickle solution" or "cure solution") and pumped directly into the green pork belly under pressure to increase the weight of the meat by about 8% to 15% of its green weight. Pumping the pork belly with cure solution helps the curing ingredients disperse in the meat more rapidly. Alternatively, the cure ingredients can be added as a dry rub to the pork belly or immersing the pork belly in a cure solution.
The cure solution performs several different functions during the curing process and after to provide certain characteristics to the pork belly. Salt acts by dehydration and altering osmotic pressure to inhibit growth of spoilage bacteria. Nitrite retards development of rancidity and produces the characteristic cured meat flavor. It also reacts with the meat pigments to stabilize the color, and most importantly inhibits the growth of Clostridium botulinum and other spoilage microorganisms. The level of nitrite allowed in curing is limited by regulation since nitrite may react with the natural amines of the meat and produce carcinogenic N-nitrosamines. Polyphosphates are also used to buffer the acidity of the liquid cure solution and also to increase the water-binding capacity in cured meats. Sugar and spices are added for flavoring. Traditionally, curing is generally considered to be complete when the curing ingredients in the pickle solution have diffused throughout the meat, and the meat has matured, that is, the color of the cured meat is fixed to a dark pink color and a portion of the water is bound. This typically takes place during smoking.
Smoking of a whole pork belly is carried out for development of a smoky flavor, additional preservation, development of color, and protection from oxidation. The term "smoking" is defined herein as a process of applying smoke to a pork belly at low heat conditions for a long period of time. The time period must be sufficient to bring the weight below about 103% of the green weight and at a temperature that does not render fat of the pork belly. Although smoke has traditionally been generated by smoldering wood or sawdust, liquid smoke is now most commonly used. Liquid smoke is prepared by destructive distillation of wood. The particle phase is removed by washing with water, and leaving the vapor phase in solution. Liquid smoke is applied by spraying, dipping, or atomizing with heat. Liquid smoke is preferred because it can be applied more uniformly. In addition, the use of liquid smoke avoids the necessity of having to clean equipment, and also avoids the health hazards of environmental pollution from smoke vapor.
Smoke (vapor or liquid) contains chemicals, principally aldehydes, phenols, ketones, and acetic acid. These chemicals are instrumental in killing yeast, mold and bacteria, and in retarding future growth. The smoke is deposited on the surface of the meat where it then penetrates the food and distributes the preservative and flavoring elements. Alternatively, the smoke may be injected directly into the meat as an ingredient of the cure solution, thus accelerating the dispersion of the chemicals contained in the smoke.
Low heat conditions for relatively long periods of time are also considered to be essential for proper traditional smoking and curing of a pork belly. Typically, smoking and curing involves placing the injected pork bellies in heated, smoke-laden currents of air in a smokehouse. Where liquid smoke is used in the pickle solution, traditional smoking and curing still requires that the injected pork bellies be heated in a smokehouse at temperatures and for time periods equivalent to those in a smokehouse with smoke vapor. Proper smokehouse temperatures for bacon do not render fat, yet are sufficiently high that moisture is drawn off rapidly. Generally, the temperature of a smokehouse for bacon is less than about 160.degree. F. Typically, the internal temperature of the pork belly is between about 126.degree. F. and about 128.degree. F. The smoking step is complete when the moisture content has been stabilized at a level to provide a smoked, cured and chilled weight below about 103% of the green weight. This ordinarily requires minimum periods of time ranging from about 6 to about 8 hours, although smoking for much longer periods of time is not uncommon. The heat accelerates loss of moisture, thereby contributing to the curing of the meat. Curing decreases microbial growth, enzyme activity, and deteriorative reactions by removing available water in the product. Smoking and curing generally brings the water activity to less than that of a green belly, typically to between about 0.90 and about 0.95. A completely cured and smoked pork belly has a stable reddish color and is firm to the touch.
The resulting cured and smoked pork belly is then conventionally chilled and sold as slab bacon, or further processed and sold as sliced bacon. Chilling brings the temperature of the smoked pork belly down from about 128.degree. F. to between about 15-35.degree. F. Below 35.degree. F., the bacon not only keeps well, but is also firm enough that it can be sliced in a slicing machine and packaged.
Alternatively, slices of the cured and smoked bacon can be partially or fully cooked after the slicing step, and then marketed as pre-cooked or cooked bacon. Bacon is cooked by rapidly applying sufficient energy to render fat. Bacon is generally considered to be pre-cooked when the yield of the bacon is about 36% to 45%. Bacon is considered cooked, or fully cooked, when the yield is about 26% to 36% of the raw product.
As can be readily appreciated, the traditional curing and smoking steps described above are expensive. Not only do these steps require long periods of time, but they also require costly equipment and consume large amounts of energy to maintain the elevated temperatures. These steps also require large facilities to store the inventory of the pork bellies at specific environmental conditions during both the curing and smoking steps.
While some food scientists have recently invented ways around the traditional smoking and curing steps, as disclosed in U.S. Pat. No. 4,957,756, the prior art has nevertheless considered the traditional step of dispersing the cure to be essential in the manufacture of bacon, especially pre-cooked bacon. The traditional smoking and curing process is even more time-consuming. Injecting pork bellies with cure solution and smoking in a smokehouse requires large storage facilities that require capital to maintain.